Towards Efficient Use of Shared Communication Media in the Timed Model

Abstract

Embedded computers are increasingly tighter integrated with each other forming distributed embedded systems that interact through a shared communication medium. Often these embedded systems perform services for safety-critical operations that require deterministic computation and predictable communication. However, since these systems are embedded, they must cope with limited resources. One fundamental challenge is to make efficient use of the shared communication medium, especially in the timed model, in which communication tends to cumulate at the end of harmonic periods of tasks.In this article, we present an approach that uses Microtasks for splitting computation and communication into several sequentially executed steps to allow for better balanced load on the communication medium in the timed model. We discuss the approach and describe its implementation in OSEK/Works with TTCAN. Logical transmission time (LTT) Completion Resume Complete Time Release Logical computation time (LCT) Start Reading input ports Suspend Logical completion Intertwined Communication and Computation with Micro-tasksIn [18], the authors suggest to split the LET into an LCT and an LTT. In this model, the results of the task are passed to the communication subsystem for transmission on the shared communication medium at the end of the LCT. Thus, communication tends to accumulate at the end of harmonic